Method of making wireless suspensions with alignment feature

ABSTRACT

Disk drive suspension load beam and flexible circuit components are juxtaposed and properly located relative to each other before welding by a series of areally distributed locator structures that intersect across the common plane between the components in aligning relation.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of United States ProvisionalApplication Serial No. 60/154,666 filed Sep. 16, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to disk drive suspensions, and, moreparticularly, to wireless disk drive suspensions in which the electricalconductor comprises a flexible circuit laminate of trace conductors, aninsulative plastic film, and a support such as a stainless steel layer.The invention further relates to an improved method for the assembly ofsuch suspensions including improvements in lowering of capital equipmentcosts, in speed and accuracy of positioning and in the maintenance ofthe accurate position before and during welding. In the invention, thealignment of the parts is with reference to themselves, and does notdepend on the accuracy of a machine vision apparatus. The inventionparticularly concerns the use of cooperating mechanical locators areallydistributed on the load beam and the flexible circuit and extendingthrough the common plane between them to enable the rapid, correctplacement of the flexible circuit on the load beam.

2. Related Art

Disk drive suspensions are quite small and the attachment thereto of thewireless electrical conductor is problematical. The components arespot-welded but must be first aligned with as perfect a registration aspossible. Machine vision relies on markers to read the position of theload beam in a welding fixture and through X, Y movements places thewireless laminate as desired. This is a slow process and only asaccurate as the machine precision in reading of the markers will allow.In addition, the accompanying fixturing is typically quite costly, and,since many suspension runs are small, there is a relatively largecapital charge on every part made in these runs. Further, presentsystems are deficient in maintaining the desired alignment, onceachieved, until welding is effected. Relative movement of the parts willdetract from the accuracy of the result although the alignment wasperfect.

SUMMARY OF THE INVENTION

It is an object of the invention, therefore, to provide a method for theassembly of disk drive suspension components. It is a further object toachieve their proper alignment without use of machine vision. It is afurther object to maintain the aligned parts free of relative movementuntil welded or otherwise fixed together. Yet another object is to havethe parts physically modified such that they will self-align solely byreference to themselves. It is a further object to provide a disk drivesuspension comprising load beam and flexible circuit components havingthe noted features.

These and other objects to become apparent hereinafter are realized inthe invention method of assembling in a predetermined alignment the loadbeam and flexible circuit components of a disk drive suspension havingproximate and distal ends that includes juxtaposing at a common contactplane a suspension load beam having a longitudinal axis and a flexiblecircuit having a longitudinal axis, the flexible circuit comprising alaminate of trace conductors, an insulative film and a metal supportlayer engaging the load beam in the contact plane, intersectinglongitudinally spaced first and second locator structures on the loadbeam with longitudinally spaced third and fourth locator structures onthe flexible circuit across the common contact plane to locate the loadbeam and flexible circuit in the predetermined alignment, and thereafterfixing the load beam and flexible circuit together in the predeterminedalignment

In this and like embodiments, typically, the method further includesextending the first and second locator structures through the commonplane, and receiving the first and second locator structures with thethird and fourth locator structures respectively, welding the flexiblecircuit metal layer to the load beam in locations spaced from thelocator structures, locating the first and second locator structures atthe suspension distal end, locating the third and fourth locatorstructures at the suspension proximate end, also forming in the loadbeam longitudinally spaced and axially aligned raised sections raisedout of the general plane of the load beam, orienting the raised loadbeam sections normal to the longitudinal axis of the load beam, formingraised section receiving recesses in the flexible circuit metal layer toform the second and fourth locator structures, and also selecting astainless steel metal layer, and intersecting fifth and sixth locatorstructures on the load beam and flexible circuit respectively across thecommon contact plane simultaneously with intersecting of the firstthrough fourth locator structures, the fifth and sixth locatorstructures being laterally offset from the longitudinal axes of the loadbeam and flexible circuit.

In a further embodiment, the invention assembly method also includesextending the first through sixth locator structures through the commonplane, and receiving the first, second and fifth locator structures withthe third, fourth and sixth locator structures respectively.

In this and like embodiments, typically, there is further includedwelding the flexible circuit metal layer to the load beam in locationsspaced from the locator structures, locating the first and third locatorstructure at the suspension distal end, locating the second, fourth andfifth and sixth locator structures at the suspension proximate end,forming in the load beam longitudinally spaced and axially alignedraised sections raised out of the general plane of the load beam as thefirst, second and fifth locator structures, orienting the raised loadbeam sections of the first and third locator structures normal to thelongitudinal axis of the load beam, and orienting the fifth locatorstructure parallel to the longitudinal axis, and forming raised sectionreceiving recesses in the metal layer to form the second, fourth andsixth locator structures, the recesses extending through the metallayer, the fifth and sixth locators being paired and located between thefirst and second paired locators and the third and fourth pairedlocators.

The invention further provides a disk drive suspension having proximateand distal ends and comprising a load beam and a flexible circuitlaminate of trace conductors, an insulative film and a metal layer, theload beam and flexible circuit being fixed together on either side of acommon plane, plural pairs of interfitting locator structures includinga distal pair of first and second locator structures, a first proximatepair of third and fourth locator structures, and a second proximate pairof fifth and sixth locator structures, the first and second pairs beinglocated on the longitudinal axes of the load beam and flexible circuit,the third pair being located laterally offset from longitudinal axes andbetween the first and second pairs at the proximate end of thesuspension, the pair members being interfitting in common planeintersecting relation.

In this and like embodiments, typically, the first, second and thirdpairs of locator structures each comprise a raised metal section and arecessed metal section opposed across the common plane, the raised metalsections are each formed in the load beam as a load beam section raisedout of the general plane of the load beam, the recessed metal sectionsare each formed of the metal layer, the raised metal sections are eachformed in the load beam as a load beam section spaced from the generalplane of the load beam, and the recessed metal sections include a recessextending through the metal layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described in conjunction with the attacheddrawings in which:

FIG. 1 is a back side plan view of the invention suspension;

FIG. 1A is a view taken on line 1A—1A in FIG. 1.

FIG. 2 is a back side plan view of the flexible circuit component of thesuspension;

FIG. 3 is a back side plan view of the load beam component of thesuspension;

FIG. 4 is front side plan view of the suspension;

FIG. 5 is a view taken on line 5—5 in FIG. 4; and

FIG. 6 is a view taken on line 6—6 in FIG. 4.

DETAILED DESCRIPTION

With reference now to the drawings in detail, in FIGS. 1-4, theinvention disk drive suspension 10 has a proximate end 12 and a distalend 14. The suspension 10 comprises load beam 16 and a flexible circuit18, a laminate of trace conductors 20, 22, an insulative plastic filmlayer 24 and a metal layer 26. The load beam 16 and flexible circuit 18are fixed together by weld points 28 to be at either side of a commonplane P—P that lies between them. A series of locator structures 32, 34are formed on the opposing load beam 16 and flexible circuit 18.

Locator structures 32, 34 include a first distal pair 35 of first andsecond locator structures 36, 38, a first proximate pair 41 of third andfourth locator structures 42, 44, and a second proximate pair 45 offifth and sixth locator structures 46, 48.

First and second pairs 35, 41 of locator structures 36, 38, 42, 44 arelocated on the coincident longitudinal axes A—A of the load beam 16 andflexible circuit 18. The second proximate pair 45 (third pair overall)of locator structures 46, 48 are located laterally offset from thelongitudinal axes A—A and between the first and second pairs 35, 41 atthe proximate end 12 of the suspension 10.

The several pair members 36, 38, and 42, 44 and 46, 48 are male-femalepairs and interfit in the assembled condition of the suspension 10.Their interfittment is across and intersects the common plane P—P.

Typically, and with reference to FIGS. 5 and 6 as well as FIGS. 1-4, thefirst, second and third pairs 35, 41 and 45 of locator structure members36, 38, 42, 44 and 46, 48 each comprise a raised metal section 52, eachformed in the load beam 16 as a load beam section raised out of thegeneral plane of the load beam formed by locally upsetting the metal.Initially, gaps 54, 56 are formed by etching the load beam 16. Theorientation of gaps 54, 56 will determine the orientation of the raisedsection 52. In FIG. 3, the gaps 54, 56 are parallel or perpendicular tothe longitudinal axis of the load beam 16. The raised portion 52 betweenthe gaps 54, 56 is deflected out of the load beam plane sufficiently topenetrate and cross the common plane P—P when the load beam 16 and theflexible circuit 18 are placed in face-to-face engagement, FIG. 1A. Asbest shown in FIG. 4 the raised section 52 typically has fold lines 52a, 52 b that provide a transition from the sloping portions 58, 62 ofthe section sloping from the load beam 16 upward and inward as shown tothe section topmost portion 64 that is parallel to the load beam generalplane, as best shown in FIG. 5. In FIG. 6, the view is at a right angleto the view in FIG. 5 and the gaps 52, 54 are best shown. The isolatedsection 52 between gaps 54, 56 is typically raised about 0.003 inch fromthe general plane of the load beam 16.

Pairs 35, 41 and 45 further include a recessed metal section 66 opposedto and registered with the raised metal section 52 across the commonplane P. The recessed metal sections 66 are each formed of the flexiblecircuit metal layer 26, as by etching into or preferably through themetal layer and film layer 24 as well, and define recesses 68 configuredto snugly receive the raised sections 52. The raised sections 52interfit with the recesses 68 in recessed metal sections 66 in a mannerto limit the movement between the load beam 16 and the flexible circuit18, thus maintaining them in the desired predetermined alignmentrelation before and during the weld step so that errors in alignment areprevented and manufacturing losses from this source reduced oreliminated.

The invention method thus includes assembling in a predeterminedalignment the load beam 16 and flexible circuit 18 of a disk drivesuspension 10 having proximate end 12 and distal end 14 by juxtaposingat a common contact plane P—P, the load beam having longitudinal axisA—A and the flexible circuit having a coincident longitudinal axis. Themethod is self-aligning in that the load beam 16 and flexible circuit 18will not fit together except as they are properly aligned with theirmale and female parts in registration. The method intersectslongitudinally spaced first and second locator structures 36, 42 (male)on the load beam with longitudinally spaced third and fourth locatorstructures 38, 44 (female) on the flexible circuit across the commoncontact plane to locate the load beam and flexible circuit in thepredetermined alignment, and thereafter fixes the load beam and flexiblecircuit together in the predetermined alignment by welding atdistributed points 28.

The method includes extending the male first and second locatorstructures 36, 42 through the common plane P—P, and receiving thesefirst and second locator structures within the female third and fourthlocator structures 38, 44, respectively. The first and third locatorstructures 36, 38 are located at the suspension distal end 14. Thesecond and fourth locator structures 42, 44 are located at thesuspension proximate end 12.

In a preferred embodiment, the method includes intersecting fifth andsixth locator structures 46 (on the load beam 16) and 48 (on theflexible circuit 18) across the common contact plane P—P simultaneouslywith intersecting of the first through fourth locator structures 36, 42,38, 44, the fifth and sixth locator structures being laterally offset asshown (and either left or right) from the longitudinal axes A—A of theload beam 16 and flexible circuit 18.

The several locator structure pairs 35, 41, and 45 are areallydistributed, e.g. as shown, and sized to have the raised metal sections52 closely interfit the opposing recesses 68. This close interfittmentkeeps the aligned load beam 16 and flexible circuit 18 from relativeshifting before and during welding rendering expensive custom fixturingunnecessary.

The invention thus provides a disk drive suspension and a method for theassembly of disk drive suspension components in their proper alignmentwithout use of machine vision, while maintaining the aligned parts freeof relative movement until welded or otherwise fixed together by usingcomponents that are physically modified such that they will self-alignsolely by reference to themselves.

We claim:
 1. A method of assembling in a predetermined alignment theload beam and flexible circuit components of a disk drive suspensionhaving proximate and distal ends, including juxtaposing at a commoncontact plane a suspension load beam having a longitudinal axis and aflexible circuit having a longitudinal axis, said flexible circuitcomprising a laminate of trace conductors, an insulative film and ametal support layer engaging said load beam in said contact plane,intersecting longitudinally spaced first and second locator structureson said load beam with longitudinally spaced third and fourth locatorstructures on said flexible circuit across said common contact plane tolocate said load beam and flexible circuit in said predeterminedalignment, and thereafter fixing said load beam and flexible circuittogether in said predetermined alignment.
 2. The assembly methodaccording to claim 1, including also extending said first and secondlocator structures through said common plane, and receiving said firstand second locator structures with said third and fourth locatorstructures respectively.
 3. The assembly method according to claim 1,including also welding said flexible circuit metal layer to said loadbeam in locations spaced from said locator structures.
 4. The assemblymethod according to claim 1, including also locating said first andsecond locator structures at said suspension distal end.
 5. The assemblymethod according to claim 1, including also locating said third andfourth locator structures at said suspension proximate end.
 6. Theassembly method according to claim 5, including also locating said firstand second locator structures at said suspension distal end.
 7. Theassembly method according to claim 6, including also forming in saidload beam longitudinally spaced and axially aligned raised sectionsraised out of the general plane of said load beam.
 8. The assemblymethod according to claim 7, including also orienting said raised loadbeam sections normal to the longitudinal axis of said load beam.
 9. Theassembly method according to claim 6, including also forming raisedsection receiving recesses in said flexible circuit metal layer to formsaid second and fourth locator structures.
 10. The assembly methodaccording to claim 1, including also selecting a stainless steel metallayer, and intersecting fifth and sixth locator structures on said loadbeam and flexible circuit respectively across said common contact planesimultaneously with intersecting of said first through fourth locatorstructures, said fifth and sixth locator structures being laterallyoffset from the longitudinal axes of said load beam and flexiblecircuit.
 11. The assembly method according to claim 10, including alsoextending said first through sixth locator structures through saidcommon plane, and receiving said first, second and fifth locatorstructures with said third, fourth and sixth locator structuresrespectively.
 12. The assembly method according to claim 11, includingalso welding said flexible circuit metal layer to said load beam inlocations spaced from said locator structures.
 13. The assembly methodaccording to claim 12, including also locating said first and thirdlocator structure at said suspension distal end.
 14. The assembly methodaccording to claim 13, including also locating said second, fourth andfifth and sixth locator structures at said suspension proximate end. 15.The assembly method according to claim 6, including also forming in saidload beam longitudinally spaced and axially aligned raised sectionsraised out of the general plane of said load beam as said first, secondand fifth locator structures.
 16. The assembly method according to claim15, including also orienting said raised load beam sections of saidfirst and third locator structures normal to the longitudinal axis ofsaid load beam, and orienting said fifth locator structure parallel tosaid longitudinal axis.
 17. The assembly method according to claim 16,including also forming raised section receiving recesses in said metallayer to form said second, fourth and sixth locator structures, saidrecesses extending through said metal layer, said fifth and sixthlocators being paired and located between said first and second pairedlocators and said third and fourth paired locators.